You will find the source files for this section in the directory tut-install/javaeetutorial5/examples/jms/clientsessionmdb/. Path names in this section are relative to this directory.

Writing the Application Components for the clientsessionmdb Example

This application demonstrates how to send messages from an enterprise
bean (in this case, a session bean) rather than from an application client,
as in the example in Chapter 23, A Message-Driven Bean Example. Figure 32–1 illustrates
the structure of this application.

The Publisher enterprise bean in this example is the enterprise-application
equivalent of a wire-service news feed that categorizes news events into six
news categories. The message-driven bean could represent a newsroom, where
the sports desk, for example, would set up a subscription for all news events
pertaining to sports.

The application client in the example injects the Publisher enterprise
bean’s remote home interface and then calls the bean’s business
method. The enterprise bean creates 18 text messages. For each message, it
sets a String property randomly to one of six values representing
the news categories and then publishes the message to a topic. The message-driven
bean uses a message selector for the property to limit which of the published
messages it receives.

Coding the Application Client: MyAppClient.java

The application client program, clientsessionmdb-app-client/src/java/MyAppClient.java, performs no JMS API operations and so is simpler than the client
program in Chapter 23, A Message-Driven Bean Example. The program uses dependency injection to obtain the Publisher
enterprise bean’s business interface:

Coding the Publisher Session Bean

The Publisher bean is a stateless session bean that has one business
method. The Publisher bean uses a remote interface rather than a local interface
because it is accessed from the application client.

The remote interface, clientsessionmdb-ejb/src/java/sb/PublisherRemote.java, declares a single business method, publishNews.

The bean class, clientsessionmdb-ejb/src/java/sb/PublisherBean.java, implements the publishNews method and its
helper method chooseType. The bean class also injects SessionContext, ConnectionFactory, and Topic resources and implements @PostConstruct and @PreDestroy callback methods. The bean class begins as follows:

The @PostConstruct callback method of the bean class, makeConnection,
creates the Connection used by the bean. The business method publishNews creates a Session and a MessageProducer and publishes the messages.

The @PreDestroy callback method, endConnection, deallocates
the resources that were allocated by the @PostConstruct callback
method. In this case, the method closes the Connection.

Coding the Message-Driven Bean: MessageBean.java

The message-driven bean class, clientsessionmdb-ejb/src/java/mdb/MessageBean.java, is almost identical to the one in Chapter 23, A Message-Driven Bean Example. However, the @MessageDriven annotation
is different, because instead of a queue the bean is using a topic with a
durable subscription, and it is also using a message selector. Therefore,
the annotation sets the activation config properties messageSelector, subscriptionDurability, clientId, and subscriptionName, as follows:

The JMS resource adapter uses these properties to create a connection
factory for the message-driven bean that allows the bean to use a durable
subscriber.

Creating Resources for the clientsessionmdb Example

This example uses the topic named jms/Topic and the
connection factory jms/ConnectionFactory, which you created
in Creating JMS Administered Objects for the Synchronous Receive Example. If you deleted the connection factory or topic, you
can create them again using targets in the build.xml file
for this example. Use the following commands to create the resources:

ant create-cf
ant create-topic

Building, Deploying, and Running the clientsessionmdb Example Using NetBeans IDE

To build, deploy, and run the application using NetBeans IDE, do
the following:

Start the Application Server, if it is not already running.

In NetBeans IDE, choose Open Project from the File menu.

In the Open Project dialog, navigate to tut-install/javaeetutorial5/examples/jms/.

Select the clientsessionmdb folder.

Select the Open as Main Project check box and the Open Required
Projects check box.

Click Open Project.

Right-click the clientsessionmdb project
and choose Build.

This task creates the following:

An application client JAR file that contains the client class
file and the session bean’s remote interface, along with a manifest
file that specifies the main class

An EJB JAR file that contains both the session bean and the
message-driven bean

An application EAR file that contains the two JAR files

Right-click the project and choose Undeploy and Deploy.

Right-click the project and choose Run.

This command
returns a JAR file named clientsessionmdbClient.jar and
then executes it.

The output of the application client in the Output pane looks like this:

The output from the enterprise beans appears in the server log (domain-dir/logs/server.log), wrapped in logging information. The Publisher session bean sends
two sets of 18 messages numbered 0 through 17. Because of the message selector,
the message-driven bean receives only the messages whose NewsType property
is Sports or Opinion.

Undeploy the application after you finish running the client. To undeploy
the application, follow these steps:

Click the Services tab.

Expand the Servers node.

Expand the Sun Java System Application Server node.

Expand the Applications node.

Expand the Enterprise Applications node.

Right-click clientsessionmdb and choose
Undeploy.

To remove the generated files, right-click the clientsessionmdb project
and choose Clean.

Building, Deploying, and Running the clientsessionmdb Example Using Ant

To build the application using Ant, do the following:

Start the Application Server, if it is not already running.

Go to the following directory:

tut-install/javaeetutorial5/examples/jms/clientsessionmdb/

To compile the source files and package the application, use
the following command:

ant

The ant command creates the following:

An application client JAR file that contains the client class
file and the session bean’s remote interface, along with a manifest
file that specifies the main class

An EJB JAR file that contains both the session bean and the
message-driven bean

An application EAR file that contains the two JAR files

The clientsessionmdb.ear file is created in the clientsessionmdb/dist directory.

To deploy the application and run the client, use the following command:

ant run

Ignore the message that states that the application is deployed at a
URL.

The output from the enterprise beans appears in the server log (domain-dir/logs/server.log), wrapped in logging information. The Publisher session bean sends
two sets of 18 messages numbered 0 through 17. Because of the message selector,
the message-driven bean receives only the messages whose NewsType property
is Sports or Opinion.

Undeploy the application after you finish running the client. Use the
following command:

ant undeploy

To remove the generated files, use the following command in the clientsessionmdb, clientsessionmdb-app-client, and clientsessionmdb-ejb directories: